1. Field of the Invention
The present invention is directed to a method for transmitting data in a data communications system, such as, but not limited to, a cable communications system.
2. Background
Conventional cable communications systems typically employ a cable modem headend that manages communications with a plurality of cable modems. The headend defines the upstream operating characteristics that enable the cable modems to send carrier signals upstream to the headend. The upstream may include multiple channels that can be assigned to the cable modems. These channels are separated from each other by operating at different frequencies.
One or more cable modems use a designated frequency channel to transmit a carrier signal carrying requests and/or data to the headend. The headend receives the upstream signal at a demodulator that interfaces with the physical spectrum interconnecting the cable modems with the headend. The demodulator recovers the underlying requests and/or grants from the carrier signal and forwards this information to a media access controller (MAC) for additional processing.
Cable Operators would like to be able to provide higher upstream bandwidth per user to compete with Fiber-to-the-Subscriber (FTTx) offerings, among others, and services to small businesses. For example, Cable Operators have stated an objective of 100 Megabits per second (Mbps) upstream throughput from a single user or group of users. Using very high orders of modulation (e.g., 1024 QAM) and wider channels in the upstream, however, are currently impractical.
Accordingly, what is needed are a practical method and system for providing increased upstream throughput in a cable communications system.